"In fact... getting back to work... was important enough that I, in fact, kept them separate... I always did what I needed to do in order to deal with the health crisis in the moment."

Mr Cheney said that despite being aware of numerous studies showing a significant link between severe heart disease and memory loss, depression and hampered decision-making, he was not worried about it and was not counselled on it either.

A blood test result seen on the very morning of 9/11 showed a surge of potassium in the vice president's blood, a potentially fatal condition known as hyperkalemia.

As Dr Reiner watched television coverage of the attacks on New York and the Pentagon and the crash of a hijacked plane in Pennsylvania, he said he thought: "Oh great, the vice president is going to die tonight from hyperkalemia."

Mr Cheney said that thanks to his treatment, he feels "fantastic" and has no real physical limits at 72.

"I fish. I hunt... I don't ski, but that's because of my knees, not my heart. So, it's been a miracle," he said.